Method for forming a fabric preform insert for a composite tank y-joint

ABSTRACT

A method and apparatus for forming a joint. A composite insert may be placed into a joint region for a first structure. The composite insert may comprise a structure having a first portion, a second portion, and a third portion all extending from a junction; and a resin impregnated into the structure to form the composite insert. The second structure may be laid up. The composite insert may be bonded to the first structure and the second structure.

This application is a divisional application of U.S. patent applicationSer. No. 12/841,502, filed Jul. 22, 2010.

BACKGROUND INFORMATION

1. Field

The present disclosure relates generally to manufacturing vehicles and,in particular, to manufacturing spacecraft. Still more particularly, thepresent disclosure relates to a method and apparatus for attaching acomposite tank to a structure of a spacecraft.

2. Background

Both a space shuttle and a launch vehicle may be examples of spacecraftwith propulsion systems. These propulsion systems may include varioustypes of propellants, such as, for example, without limitation, a solidpropellant, a liquid propellant, a mixture of both solid and liquidpropellants, and/or other suitable types of propellants or liquids.Liquid propellants may include, for example, without limitation, liquidhydrogen and/or liquid oxygen. These propellants may be stored in liquidform in cryogenic tanks. A cryogenic tank may store and/or maintainliquid propellants at very low temperatures, such as, for example,without limitation, about −297 degrees Fahrenheit in the case of liquidoxygen and about −423 degrees Fahrenheit in the case of liquid hydrogen.

In a spacecraft vehicle that uses these types of propellants, thecryogenic tank may be connected to the structure of the spacecraft usingjoints. A joint may be a location and/or place where a first structuremay be attached to a second structure. Y-joints may be used to connectthe tanks to the structures of the spacecraft. A Y-joint may be a jointin which a cross section of the joint may have a “Y” shape. In order tominimize weight, the tanks may be made of composite materials.

Y-joints have been developed for cryogenic tanks made of compositematerials. However, these Y-joints may have a less than desired abilityto carry loads between cryogenic tanks and the spacecraft.

Therefore, it would be advantageous to have a method and apparatus thattakes into account at least some of the issues discussed above, as wellas other possible issues.

SUMMARY

In one advantageous embodiment, an apparatus may comprise a structure.The structure may comprise fibers in which the structure may have afirst portion, a second portion, and a third portion all extending froma junction. A resin may be impregnated into the structure to form acomposite insert.

In another advantageous embodiment, a launch vehicle may comprise acomposite insert, a first structure, and a second structure. Thecomposite insert may comprise a structure comprising fibers and a resinimpregnated into the structure to form the composite insert. Thestructure may have a first portion, a second portion, and a thirdportion all extending from a junction. The first portion may have afirst surface and a second surface. The second portion may have a firstsurface and a second surface. The third portion may have a first surfaceand a second surface. The fibers may form a fabric comprising at leastone of woven fibers, non-woven fibers, braided fibers, and stitchedfibers and may include at least one of graphite fibers, glass fibers,and para-aramid fibers. The resin may comprise at least one of an epoxy,a bismaleimide, and a polyimide. A surface of the first structure may bebonded to the first surface of the first portion and the first surfaceof the second portion of the composite insert. A surface of the secondstructure may be bonded to the second surface of the third portion andto the second surface of the first portion of the composite insert. Thefirst structure may be a structure for one of a launch vehicle, aspacecraft, and an aircraft. The composite insert may be associated withthe first structure and the second structure to form a Y-joint betweenthe first structure and the second structure. The second structure maybe a tank configured to hold a liquid propellant. The first structureand the second structure may be comprised of a material selected from atleast one of a composite material, a metal, and a metal alloy.

In yet another advantageous embodiment, a method may be provided forforming a joint. A first portion, a second portion, and a third portionis joined to form a composite insert. A composite insert may be placedinto a joint region for a first structure. The composite insert may beresin impregnated into the structure. The second structure may be laidup. The composite insert may be bonded to the first structure and thesecond structure.

In still yet another advantageous embodiment, a method may be providedfor forming a Y-joint. A structure having a first portion, a secondportion, and a third portion all extending from a junction may beformed. The first portion may have a first surface and a second surface.The second portion may have a first surface and a second surface. Thethird portion may have a first surface and a second surface. A resin maybe infused into the structure to form a composite insert. The compositeinsert may be placed into a joint region for a first structure and asecond structure. The second structure may be laid up relative to thefirst structure. A surface of the first structure may be bonded to thefirst surface of the first portion and the first surface of the secondportion of the composite insert. A surface of the second structure maybe bonded to the second surface of the first portion and the secondsurface of the third portion of the composite insert to form the Y-jointbetween the first structure and the second structure. The firststructure and the second structure may be cured with the compositeinsert in place.

The features, functions, and advantages can be achieved independently invarious embodiments of the present disclosure or may be combined in yetother embodiments in which further details can be seen with reference tothe following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the advantageousembodiments are set forth in the appended claims. The advantageousembodiments, however, as well as a preferred mode of use, furtherobjectives, and advantages thereof, will best be understood by referenceto the following detailed description of an advantageous embodiment ofthe present disclosure when read in conjunction with the accompanyingdrawings, wherein:

FIG. 1 is an illustration of a spacecraft manufacturing and servicemethod in accordance with an advantageous embodiment;

FIG. 2 is an illustration of a spacecraft in which advantageousembodiments may be implemented;

FIG. 3 is an illustration of a spacecraft in accordance with anadvantageous embodiment;

FIG. 4 is an illustration of a spacecraft in accordance with anadvantageous embodiment;

FIG. 5 is an illustration of a cut-away side view of a portion of alaunch vehicle in accordance with an advantageous embodiment;

FIG. 6 is an illustration of a Y-joint in accordance with anadvantageous embodiment;

FIG. 7 is an illustration of a composite insert in accordance with anadvantageous embodiment;

FIG. 8 is an illustration of a cross-sectional view of a compositeinsert in accordance with an advantageous embodiment;

FIG. 9 is an illustration of a composite insert used to form a portionof a first structure and a second structure at a Y-joint in accordancewith an advantageous embodiment;

FIG. 10 is an illustration of a flowchart of a process for forming aY-joint in accordance with an advantageous embodiment;

FIG. 11 is an illustration of a flowchart of a process for creating aY-joint for a tank in accordance with an advantageous embodiment; and

FIG. 12 is an illustration of a flowchart of a process for creating acomposite insert in accordance with an advantageous embodiment.

DETAILED DESCRIPTION

Referring more particularly to the drawings, embodiments of thedisclosure may be described in the context of spacecraft manufacturingand service method 100 as shown in FIG. 1 and spacecraft 200 as shown inFIG. 2. Turning first to FIG. 1, an illustration of a spacecraftmanufacturing and service method is depicted in accordance with anadvantageous embodiment.

During pre-production, exemplary spacecraft manufacturing and servicemethod 100 may include specification and design 102 of spacecraft 200 inFIG. 2 and material procurement 104. During production, component andsubassembly manufacturing 106 and system integration 108 of spacecraft200 in FIG. 2 may take place. Thereafter, spacecraft 200 in FIG. 2 maygo through certification and delivery 110 in order to be placed inservice 112. While in service 112 by a customer, spacecraft 200 in FIG.2 may be scheduled for routine maintenance and service 114, which mayinclude modification, reconfiguration, refurbishment, and othermaintenance or service.

Each of the processes of spacecraft manufacturing and service method 100may be performed or carried out by a system integrator, a third party,and/or an operator. In these examples, the operator may be a customer.For the purposes of this description, a system integrator may include,without limitation, any number of spacecraft manufacturers and majorsystem subcontractors; a third party may include, for example, withoutlimitation, any number of vendors, subcontractors, and suppliers; and anoperator may be a country, leasing company, military entity, serviceorganization, and so on.

With reference now to FIG. 2, an illustration of a spacecraft isdepicted in which advantageous embodiments may be implemented. In thisexample, spacecraft 200 may be produced by spacecraft manufacturing andservice method 100 in FIG. 1. Spacecraft 200 may include structure 202with a plurality of systems 204 and interior 206.

Examples of systems 204 may include, for example, without limitation,one or more of propulsion system 208, electrical system 210, hydraulicsystem 212, and environmental system 214. Any number of systems may beincluded. Further, in some implementations, some of the systems may notbe needed. For example, when spacecraft 200 takes the form of a launchvehicle, environmental system 214 may be unnecessary.

Apparatus and methods embodied herein may be employed during at leastone of the stages of spacecraft manufacturing and service method 100 inFIG. 1. As used herein, the phrase “at least one of”, when used with alist of items, means that different combinations of one or more of thelisted items may be used and only one of each item in the list may beneeded. For example, “at least one of item A, item B, and item C” mayinclude, for example, without limitation, item A or item A and item B.This example also may include item A, item B, and item C or item B anditem C.

In one illustrative example, components or subassemblies produced incomponent and subassembly manufacturing 106 in FIG. 1 may be fabricatedor manufactured in a manner similar to components or subassembliesproduced while spacecraft 200 is in service 112 in FIG. 1.

Also, one or more apparatus embodiments, method embodiments, or acombination thereof may be utilized during production stages, such ascomponent and subassembly manufacturing 106 and system integration 108in FIG. 1 as an example, without limitation. These embodiments maysubstantially expedite the assembly of, or reduce the cost of,spacecraft 200.

In these examples, advantageous embodiments may be implemented to attachcomponents in propulsion system 208 to structure 202 in spacecraft 200.The different advantageous embodiments may be applied to attach anystructure within spacecraft 200 to any other structure in otherimplementations.

The different advantageous embodiments recognize and take into account anumber of different considerations. For example, without limitation, thedifferent advantageous embodiments recognize and take into account thatit may be desirable to increase the strength of currently availablejoints between the structure of a spacecraft and a tank containing apropellant above current levels with respect to various forces. Forceson the joint may include, for example, without limitation, shear forces,bending, and/or torsion at the joint between the structure of aspacecraft and a tank.

Current tanks may be metal tanks that typically use welded joints. Inthese examples, the joints may take the form of Y-joints. In otherwords, these joints may have cross-sections that have a “Y” shape.Composite tanks may be employed to provide weight savings over metaltanks. With these types of composite tanks, however, the currentlyavailable Y-joints used for these composite tanks may have less thandesired strength. Y-joints with sufficient strength may not be possiblewith currently available Y-joint designs and techniques.

The different advantageous embodiments recognize and take into accountthat the strength of a Y-joint may be increased using a softening strip.A softening strip may be a component used to reinforce a joint. Thesoftening strip may have a three-dimensional preform impregnated with,for example, without limitation, a plastic matrix to form the softeningstrip. For example, without limitation, in some cases, a softening stripmay be used with or made as part of a Y-joint. Joints made with thesoftening strip, however, still may not be able to carry loads imposedfor some cryogenic tanks.

The different advantageous embodiments also recognize and take intoaccount that a composite tank may be pressurized and configured to holda liquid and/or gas. The pressure of the composite tank and operation ofthe spacecraft during flight may generate loads that may generate largestresses at a Y-joint used to hold the composite tank to the structureof the spacecraft. As a result, with composite tanks, the load appliedto the joints may be reduced by reducing the size of the tanks.

The different advantageous embodiments recognize and take into accountthat using a composite material in the Y-joint may increase the strengthof the joint. The different advantageous embodiments also recognize andtake into account that fibers may be arranged in a desired configurationwith a resin to provide increased strength for Y-joints.

Thus, in one advantageous embodiment, an apparatus may comprise astructure with fibers in which the structure may have a first portion, asecond portion, and a third portion all extending from a junction. Thesecond layer may extend from a surface of the first layer. A resin maybe impregnated into the structure to form a composite insert.

With reference now to FIG. 3, an illustration of a spacecraft isdepicted in accordance with an advantageous embodiment. Spacecraft 300may be an example of spacecraft 200 in FIG. 2. In this illustrativeexample, spacecraft 300 may include first structure 302 and secondstructure 304.

First structure 302 may be the structure of spacecraft 300 providing aframe or other support for other components in spacecraft 300. Firststructure 302 may also be referred to as a skirt. Second structure 304may be, for example, without limitation, tank 306. Of course, secondstructure 304 may be any other component that may be located withinspacecraft 300 that is to be attached to first structure 302.

In these illustrative examples, first structure 302 may be associatedwith second structure 304 using joint 308. Joint 308 may be formed injoint region 309 between first structure 302 and second structure 304.In these illustrative examples, joint 308 may take the form of Y-joint310. Y-joint 310 may have a cross-section that has a “Y” shape. Ofcourse, joint 308 may take the form of any type of structural joint inaddition to or in place of Y-joint 310.

A first component may be considered to be associated with a secondcomponent by being secured to the second component, bonded to the secondcomponent, fastened to the second component, fastened and bonded to thesecond component, associated with the second component by a combinationof the above, and/or connected to the second component in some othersuitable manner. The first component also may be connected to the secondcomponent by using a third component. The first component may also beconsidered to be associated with the second component by being formed aspart of and/or an extension of the second component.

In these illustrative examples, composite insert 312 may be used to formjoint 308. In particular, when composite insert 312 is configured foruse in forming Y-joint 310, composite insert 312 may be placed intojoint region 309. Composite insert 312 may comprise structure 314 andresin 316. Resin 316 may be impregnated into structure 314 to formcomposite insert 312. In this illustrative example, structure 314 may bereferred to as preform 317 prior to resin 316 being impregnated intostructure 314. Resin 316 may be cured in structure 314. Preform 317 maybe a dry perform prior to resin 316 being impregnated into preform 317in these examples.

Structure 314 may comprise fibers 318 and may have first portion 320,second portion 321, and third portion 322. First portion 320, secondportion 321, and third portion 322 may form Y-shape 326. As depicted,first portion 320, second portion 321, and third portion 322 all mayextend from junction 324.

In this illustrative example, first portion 320 may have first surface330 and second surface 331 located opposite of first surface 330. Secondportion 321 may have first surface 332 and second surface 333 locatedopposite of first surface 332. Third portion 322 may have first surface334 and second surface 335 located opposite of first surface 334.

In one advantageous embodiment, surface 328 of first structure 302 maybe bonded to first surface 330 of first portion 320 and first surface332 of second portion 321 of composite insert 312. Surface 336 of secondstructure 304 may be bonded to second surface 331 of first portion 320and second surface 335 of third portion 322. As depicted, at least aportion of surface 328 of first structure 302 may be located opposite ofsurface 336 of second structure 304.

In another advantageous embodiment, composite insert 312 may beassociated with first structure 302 and second structure 304 such thatcomposite insert 312 may form a part of these two structures. Forexample, without limitation, first end 338 of first portion 320 may bebonded to first edge 340 of wall 342 for first structure 302 and tofirst edge 344 of wall 346 for second structure 304. First end 338bonded to first edge 340 and first edge 344 may form first scarf joint348 for first portion 320.

In these illustrative examples, a scarf joint may have faces thatinclude overlapping sections or surfaces to connect an end to a numberof edges. For example, without limitation, first scarf joint 348 mayhave faces that may include overlapping sections or surfaces to connectfirst end 338 of composite insert 312 to first edge 340 of wall 342.

Further, second end 350 of second portion 321 may be bonded to secondedge 352 of wall 342 in first structure 302. Second end 350 bonded tosecond edge 352 may form second scarf joint 354 for second portion 321.Third end 356 of third portion 322 may be bonded to second edge 358 ofwall 346 for second structure 304. Third end 356 bonded to second edge358 of wall 346 may form third scarf joint 360. In this manner,composite insert 312 may be formed as a part of first structure 302 andsecond structure 304 in forming Y-joint 310.

In the different advantageous embodiments, the bonding of the differentends of composite insert 312 with the different edges of wall 342 andwall 346 may be performed in a number of different ways. This bondingmay be performed using, for example, without limitation, adhesives,welding, fasteners, curing processes, and/or other suitable processes.

In these illustrative examples, fibers 318 may be configured in a numberof different ways to form Y-shape 326 having junction 324. For example,without limitation, fibers 318 may be configured as fabric 364. Fabric364 may be any configuration of fibers 318 that may form a flexiblematerial. This flexibility may be present prior to curing of resin 316impregnated in preform 317 to form composite insert 312. In particular,fabric 364 may be a network formed by fibers 318. Further, fibers 318may be configured to have more than one direction in fabric 364.

Fabric 364 may take a number of different forms. For example, fabric 364may be at least one of woven fabric 366, non-woven fabric 368, and othersuitable forms of fabric. Woven fabric 366 may be formed by weavingfibers 318. In other words, threads made from fibers 318 may beinterlaced with each other to form woven fabric 366. These threads maybe referred to as, for example, without limitation, tows. In thismanner, fibers 318 may have at least two or more directions in fabric364.

Non-woven fabric 368 may be formed by associating fibers 318 with eachother. This association may be made in a number of different ways. Forexample, without limitation, non-woven fabric 368 may be formed bystitching fibers 318, braiding fibers 318, and/or using other mechanismsfor associating fibers 318 with each other. Additionally, non-wovenfabric 368 may comprise fibers 318 that may be joined to each other byentangling the fibers to each other.

In these illustrative examples, fibers 318 may be comprised of a numberof different types of materials. For example, without limitation, fibers318 may be comprised of at least one of graphite fibers, glass fibers,para-aramid fibers, and other suitable types of fibers. Additionally,resin 316 may take a number of different forms. For example, withoutlimitation, resin 316 may be comprised of at least one of an epoxy, abismaleimide, a polyimide, and other suitable types of resins.

In these illustrative examples, composite insert 312 may be cured priorto use in forming Y-joint 310. Composite insert 312 may be onlypartially cured in some illustrative examples. In other advantageousembodiments, additional curing of composite insert 312 may occur formingY-joint 310.

The illustration of spacecraft 300 in FIG. 3 is not meant to implyphysical or architectural limitations to a manner in which differentadvantageous embodiments may be implemented. Other components inaddition to and/or in place of the ones illustrated may be used. Somecomponents may be unnecessary in some advantageous embodiments. Also,the blocks are presented to illustrate some functional components. Oneor more of these blocks may be combined and/or divided into differentblocks when implemented in different advantageous embodiments.

For example, first structure 302 and second structure 304 may bestructures used in another vehicle other than spacecraft 300. Forexample, these structures may be used in an aircraft. In otheradvantageous embodiments, spacecraft 300 may take the form of, forexample, without limitation, a shuttle, a launch vehicle, a combinationof a space shuttle and a launch vehicle, and/or some other suitablevehicle capable of space travel.

With reference now to FIG. 4, an illustration of a spacecraft isdepicted in accordance with an advantageous embodiment. In this example,launch vehicle 400 is an example of one implementation of spacecraft 300in FIG. 3. Launch vehicle 400 has forward section 402 and aft section404. Launch vehicle 400 may have longitudinal axis 406. Launch vehicle400 is an example of a spacecraft in which Y-joint 310 in FIG. 3 may beimplemented. Section 408 may be an example of a portion of launchvehicle 400 in which Y-joint 310 may be found and/or implemented.

With reference now to FIG. 5, an illustration of a cut-away side view ofa portion of a launch vehicle is depicted in accordance with anadvantageous embodiment. In this diagram, a cut-away side view ofsection 408 of launch vehicle 400 is depicted. This view may allow theinterior of launch vehicle 400 to be presented.

In this example, arrow 501 points towards the forward part of launchvehicle 400, while arrow 503 points to the aft portion of launch vehicle400.

In this illustrative example, tank 504 in launch vehicle 400 may includedome 506, dome 508, and wall 510. Wall 510 may be a cylindrical wall inthese examples. Wall 510 may be attached to forward skirt 512 and aftskirt 514. Wall 510 may be located between forward skirt 512 and aftskirt 514. In this example, wall 510 may be a pressurized portion oftank 504, while forward skirt 512 and aft skirt 514 may be located atunpressurized portions of tank 504.

Forward skirt 512 and aft skirt 514 are examples of structures to whichtank 504 may be attached. In these examples, these different structuresmay be cylindrical in form, of which only a cross-section may be seen inFIG. 5. In this depicted example, Y-joint 520 and Y-joint 522 may bepresent. Y-joint 520 may be formed from the intersection of dome 506,wall 510, and forward skirt 512. Y-joint 522 may be formed at theintersection of dome 508, wall 510, and aft skirt 514. In theseexamples, Y-joint 520 and Y-joint 522 may be continuous incircumferential direction around axis 524.

In these examples, tank 504 may take the form of a composite cryogenictank. Tank 504 may hold a propellant, such as, for example, withoutlimitation, liquid hydrogen and/or liquid oxygen. In this example, tank504 may hold liquid hydrogen. Further, tank 504 may be greater thanabout 16 feet in diameter. A more detailed illustration of Y-joint 520in section 530 is shown in FIG. 6 below.

Turning now to FIG. 6, an illustration of a Y-joint is depicted inaccordance with an advantageous embodiment. As illustrated in section530, forward skirt 512 may include outboard skin 600, core 602, andinboard skin 604. However, in other illustrative examples, forward skirt512 may take the form of a solid laminate without a core.

In this illustrative example, outboard skin 600 and inboard skin 604 maybe face sheets with core 602 being located between those face sheets.Core 602 may be a low-density structure element. Core 602 may be used,for example, without limitation, to transmit loads between outboard skin600 and inboard skin 604. Core 602 may take various forms. For example,without limitation, core 602 may have a fluted, honeycombed, or othersuitable type of form. In these examples, a fluted structure may be adesired structure for core 602.

In this illustrative example, Y-joint 520 may be formed at theintersection of dome 506, wall 510, and forward skirt 512. Dome 506 andwall 510 form surface 605 for tank 504. Y-joint 520 may be formed usingcomposite insert 606. Composite insert 606 may be an example of oneimplementation for composite insert 312 in FIG. 3. Composite insert 606may be bonded to inboard skin 604 and tank 504.

In the different advantageous embodiments, composite insert 606 may beco-bonded to inboard skin 604 and tank 504 along with the bonding ofinboard skin 604 to tank 504. In other words, these different componentsmay be co-bonded to each other at the same time. When forward skirt 512takes the form of a solid laminate without a core, composite insert 606may be bonded to the inboard side of the solid laminate.

The co-bonding, in these examples, may take the form of one or morecuring processes in which the composite components in composite insert606, inboard skin 604, and tank 504 may be cured to bond thesecomponents to each other. In other illustrative examples, compositeinsert 606, inboard skin 604, and tank 504 may be cured separately andthen subsequently bonded together.

The illustration of tank 504 is presented for purposes of depicting onemanner in which different advantageous embodiments may be implemented.Composite insert 606, in the different advantageous embodiments, may beapplied to other tank and/or skirt geometries. For example, withoutlimitation, although tank 504 is shown with a cylindrical wall, othertank configurations may be employed. As an example, a conical wall forwall 510 may be used. Also, other tanks may not be readily symmetric.Regardless of the structure or shape of tank 504, a Y-joint may be used.

With reference now to FIG. 7, an illustration of a composite insert isdepicted in accordance with an advantageous embodiment. In thisillustrative example, a perspective view of a portion of compositeinsert 606 is depicted in accordance with an advantageous embodiment.

As illustrated, composite insert 606 may comprise structure 700.Structure 700 may have first portion 702, second portion 704, and thirdportion 706 all extending from junction 708. First portion 702, secondportion 704, and third portion 706 may form cross-section 709 in theseillustrative examples. Additionally, a resin (not shown), such as resin316 in FIG. 3, may be impregnated into first portion 702, second portion704, and third portion 706 in structure 700 to form composite insert606. The resin may be cured in composite insert 606.

First portion 702 may have first surface 710 and second surface 712located opposite of first surface 710. Second portion 704 may have firstsurface 714 and second surface 716 located opposite of first surface714. Third portion 706 may have first surface 718 and second surface 720located opposite of first surface 718.

First surface 710 of first portion 702 and first surface 714 of secondportion 704 may be bonded to inboard skin 604 of forward skirt 512 inFIG. 6. Second surface 712 of first portion 702 and second surface 720of third portion 706 may be bonded to surface 605 of tank 504 in FIG. 6.

In this illustrative example, structure 700 may extend in a cylindricalor circular form to wrap around tank 504 in FIGS. 5 and 6. In otheradvantageous embodiments, multiple structures, such as structure 700,may be used to form Y-joint 520 to hold tank 504 to wall 510 and forwardskirt 512 in FIG. 5.

Turning next to FIG. 8, an illustration of a cross-sectional view of acomposite insert is depicted in accordance with an advantageousembodiment. In this illustrative example, composite insert 606 isillustrated in a cross-sectional view taken along lines 8-8 in FIG. 7.As depicted in this illustrative example, structure 700 of compositeinsert 606 may be comprised of fibers 800. Further, resin 802 may beimpregnated in structure 700. Resin 802 may be cured in structure 700.In other words, composite insert 606 may be pre-cured before being usedto form a joint.

With reference now to FIG. 9, an illustration of a composite insert usedto form a portion of a first structure and a second structure at aY-joint is depicted in accordance with an advantageous embodiment. Inthis illustrative example, composite insert 900 may be an example of oneimplementation for composite insert 312 in FIG. 3.

As depicted in this example, composite insert 900 may comprise structure902 having first portion 904, second portion 905, and third portion 906all extending from junction 908. In this example, first end 912 of firstportion 904 may be bonded to first edge 914 of wall 916 of firststructure 918 and first edge 920 of wall 922 of second structure 924.First end 912 bonded to first edge 914 of wall 916 and first edge 920 ofwall 922 may form scarf joint 926.

Further, second end 928 of second portion 905 may be bonded to secondedge 930 of wall 916 of first structure 918. Second end 928 bonded tosecond edge 930 of wall 916 may form scarf joint 932. Third end 934 ofthird portion 906 may be bonded to second edge 936 of wall 922 of secondstructure 924. Third end 934 bonded to second edge 936 of wall 922 mayform scarf joint 938.

With reference now to FIG. 10, an illustration of a flowchart of aprocess for forming a Y-joint is depicted in accordance with anadvantageous embodiment. The process illustrated in FIG. 10 may be usedto create Y-joint 310 between first structure 302 and second structure304 in FIG. 3.

The process may begin by placing composite insert 312 into joint region309 for first structure 302 and second structure 304 (operation 1000).Composite insert 312 may comprise structure 314 and resin 316impregnated in structure 314. In other words, structure 314 may bepreform 317 prior to resin 316 being impregnated into structure 314 toform composite insert 312. Preform 317 with resin 316 may be cured inoperation 1000.

The process may then lay up and/or position second structure 304relative to first structure 302 (operation 1002). Thereafter, compositeinsert 312 may be bonded to first structure 302 and second structure 304(operation 1004), with the process terminating thereafter. As discussedabove, this bonding may be performed using various mechanisms. Thesemechanisms may include, for example, without limitation, co-curing,curing, adhesive bonding, and/or other suitable bonding techniques.

With reference now to FIG. 11, an illustration of a flowchart of aprocess for creating a Y-joint for a tank is depicted in accordance withan advantageous embodiment. The process illustrated in FIG. 11 may be amore-detailed example of one implementation for the process illustratedin FIG. 10. The process illustrated in FIG. 11 may be used to create aY-joint between a composite cryogenic tank and a cryogenic skirt. As oneillustrative example, this process may be used to create Y-joint 520between tank 504 and forward skirt 512 in FIGS. 5-6.

The process may begin by laying up dome 506 and wall 510 of tank 504(operation 1100). Thereafter, composite insert 606 may be placed into ajoint region for tank 504 and forward skirt 512 (operation 1102). Inoperation 1102, composite insert 606 may be placed into the joint regionand positioned with an adhesive film.

Next, forward skirt 512 may be laid up (operation 1104). Forward skirt512 may be laid up over the area where dome 506 and wall 510 may belocated along with composite insert 606. The components may then becured (operation 1106), with the process terminating thereafter.

In operation 1106, the curing may be performed using heat, pressure, ora combination of the two. This curing operation may be performed usingan autoclave or some other suitable oven. In other advantageousembodiments, the components may be cured using an electron beam.

The result of the curing operation in operation 1106 may be Y-joint 520in FIG. 5. This joint may have increased load capabilities as comparedto currently available Y-joints.

With reference now to FIG. 12, an illustration of a flowchart of aprocess for creating a composite insert is depicted in accordance withan advantageous embodiment. The process illustrated in FIG. 12 may beused to create a composite insert for use in the different operationsillustrated in FIGS. 10 and 11. For example, without limitation, theprocess illustrated in FIG. 12 may be used to create composite insert312 in FIG. 3 and/or composite insert 606 in FIGS. 6-8.

The process may begin by forming preform 317 (operation 1200). In theseillustrative examples, preform 317 may have first portion 320, secondportion 321, and third portion 322 all extending from junction 324. Inthese examples, preform 317 may have Y-shape 326. Preform 317 may beformed by creating fabric 364 from fibers 318 in the desired form. Inthese illustrative examples, preform 317 may be formed by, for example,without limitation, braiding fibers 318, weaving fibers 318, stackingwoven materials, performing z-pinning, or performing some other suitabletype of process using fibers 318.

Next, resin 316 may be infused into preform 317 (operation 1202). Inthis illustrative example, infusing resin 316 into preform 317 may beone example of impregnating resin 316 into preform 317 to createcomposite insert 312.

In these illustrative examples, the infusion in operation 1202 may beperformed by placing a powder onto preform 317 and working the powderinto preform 317. For example, without limitation, the infusion inoperation 1202 may involve vibrating the preform and applying heat andpressure to perform the infusion into composite insert 312. The heat andpressure applied in operation 1202 may be performed using an autoclave,an oven, a device for applying localized heat and pressure, or someother suitable mechanism.

The infusion of resin 316 into preform 317 in operation 1202 may formcomposite insert 312. The heat and/or pressure may cure composite insert312. In other illustrative examples, resin 316 may take another formother than a powder. For example, without limitation, resin 316 may be aliquid, a paste, a solid, or some other suitable type of compound.

The process may then shape composite insert 312 (operation 1204). Inoperation 1204, composite insert 312 may be machined, cut, or shapedusing some other suitable process to form the desired dimensions for usein Y-joint 310. The process may etch the different surfaces of compositeinsert 312 (operation 1206). The etching may be performed to allow anadhesive film to be attached to the surface of the composite insert.

The process may then attach an adhesive film to the different surfacesof composite insert 312 (operation 1208), with the process terminatingthereafter. The adhesive film may allow composite insert 312 to beattached or cured to, for example, without limitation, the skirt anddome of a tank and/or other structures during a curing process.

The flowcharts and block diagrams in the different depicted embodimentsillustrate the architecture, functionality, and operation of somepossible implementations of apparatus and methods in differentadvantageous embodiments. In this regard, each block in the flowchartsor block diagrams may represent a module, segment, function, and/or aportion of an operation or step.

In some alternative implementations, the function or functions noted inthe block may occur out of the order noted in the figures. For example,in some cases, two blocks shown in succession may be executedsubstantially concurrently, or the blocks may sometimes be executed inthe reverse order, depending upon the functionality involved. Also,other blocks may be added in addition to the illustrated blocks in aflowchart or block diagram.

For example, without limitation, other operations may be included, suchas preparation for bonding, shimming, caul-plating, and other suitableoperations. Additionally, some of the different operations may beperformed concurrently or in different orders, depending on theparticular implementation.

Thus, the advantageous embodiments may provide a method and apparatusfor increasing the strength of a joint between structures. The differentadvantageous embodiments may include a composite insert in which thecomposite insert comprises a preform and a resin. The preform maycomprise fibers in which the preform may have a first portion, a secondportion, and a third portion all extending from a junction. The firstportion, the second portion, and the third portion may form a Y-shapefor the preform. The resin may be impregnated into the preform to createthe composite insert. The composite insert may be used to form aY-joint.

With the different advantageous embodiments, increased strength inY-joints may be provided for different structures as compared tocurrently used Y-joints. Additionally, when used with compositematerials, the different advantageous embodiments may be integrated aspart of those structures. Further, the different advantageousembodiments may be used with objects other than spacecraft as shown inthese examples. For example, without limitation, the composite insertmay be used in a joint for structures in a submarine, an aircraft, abuilding, a dam, a manufacturing facility, a power plant, a tank, orsome other suitable object.

The description of the different advantageous embodiments has beenpresented for purposes of illustration and description and is notintended to be exhaustive or limited to the embodiments in the formdisclosed. Many modifications and variations will be apparent to thoseof ordinary skill in the art. Further, different advantageousembodiments may provide different advantages as compared to otheradvantageous embodiments.

The embodiment or embodiments selected are chosen and described in orderto best explain the principles of the embodiments, the practicalapplication, and to enable others of ordinary skill in the art tounderstand the disclosure for various embodiments with variousmodifications as are suited to the particular use contemplated.

1-14. (canceled)
 15. A method for forming a joint, the methodcomprising: joining a first portion, a second portion, and a thirdportion to form a composite insert; placing the composite insert into ajoint region for a first structure; resin impregnating the compositeinsert into the first structure; laying up a second structure; andbonding the composite insert to the first structure and the secondstructure.
 16. The method of claim 15, wherein the first portion has afirst surface and a second surface, the second portion has a firstsurface and a second surface, and the third portion has a first surfaceand a second surface and wherein the step of bonding the compositeinsert to the first structure and the second structure comprises:bonding a surface of the first structure to the first surface of thefirst portion and the first surface of the second portion of thecomposite insert; and bonding a surface of the second structure to thesecond surface of the first portion and the second surface of the thirdportion of the composite insert to form the joint between the firststructure and the second structure.
 17. The method of claim 15, whereinthe step of bonding the composite insert to the first structure and thesecond structure comprises: bonding a first end of the first portion toa first edge of a wall of the first structure and to a first edge of awall of the second structure; bonding a second end of the second portionto a second edge of the wall of the first structure; and bonding a thirdend of the third portion to a second edge of the wall of the secondstructure.
 18. The method of claim 15, wherein the step of bonding thecomposite insert to the first structure and the second structurecomprises: curing the first structure and the second structure with thecomposite insert in place.
 19. The method of claim 15 furthercomprising: forming the structure; and infusing the resin into thestructure to form the composite insert.
 20. A method for forming aY-joint, the method comprising: forming a structure having a firstportion, a second portion, and a third portion all extending from ajunction in which the first portion has a first surface and a secondsurface, the second portion has a first surface and a second surface,and the third portion has a first surface and a second surface; andinfusing a resin into the structure to form a composite insert.
 21. Themethod of claim 20 further comprising: placing the composite insert intoa joint region for a first structure and a second structure.
 22. Themethod of claim 21 further comprising: laying up the second structurerelative to the first structure.
 23. The method of claim 22 furthercomprising: bonding a surface of the first structure to the firstsurface of the first portion and the first surface of the second portionof the composite insert.
 24. The method of claim 21 further comprising:bonding a surface of the second structure to the second surface of thefirst portion and the second surface of the third portion of thecomposite insert to form the Y-joint between the first structure and thesecond structure.
 25. The method of claim 24 further comprising: curingthe first structure and the second structure with the composite insertin place.